Patch few bugs in distutils.ext.

This version seems able to install at list the empty package

distutils.ext/obidistutils/serenity/virtual.py

@@ -0,0 +1,68 @@
+'''
+Created on 2 oct. 2014
+
+@author: coissac
+'''
+
+import os
+import sys
+import venv
+
+from distutils.errors import DistutilsError
+from obidistutils.serenity.globals import local_virtualenv  # @UnusedImport
+from obidistutils.serenity.checkpython import   which_virtualenv,\
+                                                is_python_version, \
+                                                is_a_virtualenv_python
+                                                
+
+    
+    
+def serenity_virtualenv(envname,package,version,minversion='3.4',maxversion=None):
+        
+    #
+    # Checks if we are already running under the good virtualenv
+    #
+    ve = which_virtualenv(full=True)
+    if ve == os.path.realpath(envname) and is_python_version(minversion=minversion,maxversion=maxversion):
+        return sys.executable
+        
+    #
+    # Check if the virtualenv exist
+    # 
+        
+    python = None
+    
+    if os.path.isdir(envname):
+        python = os.path.join(envname,'bin','python')
+        ok = (is_python_version(python,
+                                minversion=minversion,
+                                maxversion=maxversion) and 
+              is_a_virtualenv_python(python))
+        
+        #
+        # The virtualenv already exist but it is not ok
+        #
+        if not ok:
+            raise DistutilsError("A virtualenv %s already exists but not with the required python")
+                 
+    else:
+        ok = False
+                
+        
+    #
+    # Creates a new virtualenv
+    #
+    if not ok:
+        venv.create(envname, 
+                    system_site_packages=False, 
+                    clear=True, 
+                    symlinks=False, 
+                    with_pip=True)
+        
+        # check the newly created virtualenv
+        return serenity_virtualenv(envname,package,version)
+    
+    return os.path.realpath(python)
+    
+    
+